The Merchant Customer Exchange, a new payment system being designed by retailers, is just the tip of the iceberg. Major merchants such as Walmart are also challenging some of the payments industry's hard-fought victories, such as the recently proposed multi-billion dollar settlement over interchange pricing. (Image: Bloomberg News)

Taking a Pass

Many of the mobile wallets backed by large companies are built around phones designed with Near Field Communication chips for payment, but Apple seems to regard NFC as an optional ingredient. Its Passbook, which is less focused on payments, already has strong supporters like Starbucks and Amex. (Image: Bloomberg News)

Squaring Off

Square's mobile card reader is a hit among smaller merchants, but it is less successful with larger ones. As it swims upstream, Square faces fierce competition from the likes of PayPal, VeriFone and even Groupon. Pictured: Square CEO Jack Dorsey (Image: Bloomberg News)

Security Split

Mobile wallets are supposed to have stronger security, but a few early entrants, such as Google and Square, have faced harsh criticism for perceived and actual security flaws. Will consumers shun these new payment methods, or will they forgive their security snafus? (Image: Bloomberg News)

ISOs Under Attack

As new payment systems emerge, so do new distribution models. Groupon and Fiserv are both choosing to distribute their new payment readers without the help of independent sales organizations. (Image: ThinkStock)